Abstract We present the results of a number of high resolution radio
observations of the AGN 1156+295. These include multi-epoch and
multi-frequency VLBI, VSOP, MERLIN and VLA observations made over
a period of 50 months. The 5 GHz MERLIN images trace a straight
jet extending to ~
at
.
Extended low brightness emission was detected in the MERLIN
observation at 1.6 GHz and the VLA observation at 8.5 GHz with a
bend of ~
at the end of the 2 arcsec jet. A region
of similar diffuse emission is also seen about 2 arcsec south
of the radio core. The VLBI images of the blazar reveal a core-jet
structure with an oscillating jet on a milli-arcsecond (mas)
scale which aligns with the arcsecond jet at a distance of several
tens of milli-arcseconds from the core. This probably indicates
that the orientation of the jet structure is close to the line of
sight, with the northern jet being relativistically beamed toward
us. In this scenario the diffuse emission to the north and south
is not beamed and appears symmetrical. For the northern jet at the
mas scale, proper motions of
, and
are measured in three distinct components of the
jet (
q0=0.5,
H0=65 km s
-1 Mpc
-1 are used through
out this paper). Highly polarised emission is detected on VLBI
scales in the region in which the jet bends sharply to the
north-west. The spectral index distribution of the source shows
that the strongest compact component has a flat spectrum, and the
extended jet has a steep spectrum. A helical trajectory along the
surface of a cone was proposed based on the conservation laws for
kinetic energy and momentum to explain the observed phenomena,
which is in a good agreement with the observed results on scales
of 1 mas to 1 arcsec.